Indicating device for electric clocks



Oct. 6, 1942. MENKlN 2,293,838

INDICATING DEVICE FOR ELECTRIC CLOCKS Filed July 2, 1940 55 24 )e l LINVENTOR. MA x MEN/ IN A TTOR/VEY Patented Oct. 6, 1942 INDICATINGDEVICE FOR ELECTRIC CLOCKS Max Menkin, New York, N. Y.

Application July 2, 1940, Serlai No. 343,519

2 Claims.

This invention relates to indicating devices for electric clocks and hasfor its general object and purpose to provide a simply constructed andreliably operating device for indicating an interruption of the electriccurrent for a sufficient period of time to impair the accurate timingfunction of the clock mechanism.

It is a more particular object of the invention to provide such anindicating device for electric clocks of the self-starting, synchronousmotor driven type in which the accurate time keeping qualities of theclock are dependent on the freedom from interruption of the alternatingmotor energizing current.

It is a characteristic feature of the present invention to provide anindicating device for the above purpose embodying a movable indicatingelement which is normally active while the clock motor isuninterruptedly supplied with energizing current and'becomes inactive toindicate a failure of the current when the current flow to said motor isinterrupted, but without influencing the continuity of flow of thecurrent to the motor field and the operation of the clock mechanism ineither condition of said indicating element.

In a practical embodiment of the invention, I prefer to employ avari-colored rotatable indicating element and to provide a synchronousmagnetic field for operating said element by extending several of thelaminations of the clock motor field core to form pole pieces so that,after initial manual rotation of the indicating element, it willthereafter be maintained active by the continuous supply of current tosaid motor, and upon interruption in the current supply of the slightestduration, rotation of said indicating element will cease. Thus theattention is called to the fact, after the supply of current has beenresumed and the operation of the clock continued, that the indicatedtime is inaccurate and that the clock should be reset.

' With the above and other objects in view, the invention consists in anindicating device for electric clocks, and in the combination andarrangement of the several parts, as will be here- Fig. 1 is a frontelevation, partly broken away showing one practical form of theindicating device.

Fig. 2 is a vertical sectional view, taken substantially on the line 2-2of Fig. 1.

Fig. 3 is a rear elevation, the rear cover plate being removed, and IFig. ,4 is a horizontal sectional view taken substantially on the line4-4 of Fig. 2.

Referring in detail to the drawing, 5 generally indicates an electricclock of the self-starting type, which may be of any suitable orpreferred construction well known in the art. For the purpose of thisexplanation, it is deemed necessary to show only sufficient of the clockmechanism as will enable the application-and operation of my presentinvention to be clearly understood. Therefore, it will suiiice to statethat the clock includes the outer casing 6 of any desired ornamentalform, within which the self-starting alternating current synchronousmotor I is suitably mounted to operate the clock mechanism indicated at8. This motor includes the field core 9 of the coil I 0, said core beingof the usual soft iron laminated construction and having the pole piecesindicated at Ii.

The indicating device, in the form selected for illustration, includes ashaft or spindle l2 suitably mounted or supported in the clock case forfree rotation and having one end thereof extended rearwardly through anopening in the rear cover plate l3 of the case and provided with asuitable finger piece I whereby said shaft may conveniently be manuallyrotated. To the forward end of this shaft and adjacent the rear face ofthe dial plate ii of the clock an indicating disk I6 is fixed. The frontsurface of this disk is provided with radially extending, alternating,contrastingly colored areas visible through the opening I! in the dialplate I5. As an example, I may provide the surface of said disk withwhite areas l8 alternating with the red areas I9. Also, I preferablyprovide said disk with the serpentine or undulating perimeter 20 whichis likewise visible through the opening II. This feature, in connectionwith the vivid color contrast between the surface areas l8 and I9,attracts the attention of the observer to said rotating disk in thenormal operation of the clock.

After the rotation of the indicating disk I8 is started by the manualoperation of the shaft l2, magnetic means is provided for continuing therotation of said disk while there is an uninterrupted supply ofalternating electric current to the motor I. In one simple and practicalembodiment of this magnetic operating means for the indicator, I formseveral of the laminations of the stator or field core 9 of the motor Iwith the extensions 2|, which, as herein shown, extend vertically abovethe parallel side legs of said core and terminate at their upper ends inthe inwardly projecting spaced apart pole pieces 22. Th inner edges orthese pole pieces are closely spaced in concentric relation from amagnetizable disk or rotor 23 fixed upon the shaft i2, the confrontingedges of said disk and pole pieces being toothed in the conventionalmanner, as shown. At one side of the disk 23, a fly wheel 24 is looselymounted on the shaft I2, suitable connecting means (not shown) beinginterposed between said disk and fly wheel. As the use of such fly wheelis commonly employed in this art, further detail description thereof isnot required. Its purpose is to insure the continued activ operation ofthe indicator as the notches or the pole pieces 22 and disk 23 registerwith each other.

In the operation of the above described device, it will be understoodthat when operating current is supplied to the motor I, a magnetic fluxfield is established between the pole pieces 22 and after the disk IIhas been initially rotated by manual operation of the shaft I2, saidmagnetic field causes the rotation of said shaft and the disk I8 so longas the supply of operating current to the motor 1 is not interrupted.However, upon the slightest interruption in the current supply,

the rotation of the shaft [2 will cease and the disk l8 will bestationary or inactive, which condition may be noted by the observerthrough the opening II. when the supply of current is again resumed, theconstruction of the pole pieces and interposed rotor prevents movementor the indicating device, while the full current supply to motor I againoperates the clock mechanism. The fact that the indicating disk I6 isnot moving or rotating, informs the observer that there has been anappreciable interruption in the current and that the indicated time isinaccurate. The clock is then reset and the shaft I2 manually operatedso that the indicating functio of the disk I6 is again established. Itwill thus be seen that I have provided a simple and reliably operatingindicating device which is actively influenced by the motor energizingcurrent so long as the motor is uninterruptedly supplied with saidcurrent and that the said device is instantly rendered inactive uponinterruption oi the current supply, but without influencing-thecontinuity oi the flow of current to the motor and the operation of theclock mechanism in either condition of the said indicating device. Ihave disclosed my novel indicator, in one application thereof, to aself-starting electric clock, but it will be more or less obvious thatthe invention is not necessarily limited to such application as it mayalso be applied in various other instances where there is a likelihoodof interruption in the supply of electric energy to an electricallydriven instrument. Likewise, the invention is not limited in itsessentials to the particular practical embodiment of the combination andarrangement of cooperating elements which I have selected for purposesof illustration, but is manifestly susceptible of embodiment in numerousother structural forms. Accordingly, I reserve the privilege ofresorting to all such legitimate changes in these respects as may befairly comprehended within the spirit and scope of the appended claims.

I claim:

1. In combination with a clock and a selfstarting synchronous operatingmotor therefor, a rotatable indicating element associated with theclock, and magnetic control means therefor operatively influenced by themotor field to continuously rotate said element in one direction whilethe currentsupply to the motor is maintained and to render said elementinactive upon current interruption and after the current supply andoperation or th clock is re-established.

2. In combination with a self-starting clock including timing mechanismand an operating rotor therefor, a current-failur indicating element andan operating rotor therefor, and a synchronous clock motor having meansfor producing a single magnetic field for energizing both of said rotorsto continuously actuate said timing mechanism and indicating elementwhil the current supply to the motor is maintained, said rotors being soconstructed and arranged relative to the magnetic field that only thefirst named rotor is reenergized upon resumption of current supply afterfailure, while said second'named rotor and indicating element are againcontinuously actuated by the motor field only after initial manualrotation is imparted to the latter rotor.

MAX MENKIN.

